In hydro I feed Cal/Mag at about 100% of what the bottle says until they get to flower then I start bumping it up. You cant really over feed cal/mag and not feeding enough can cause problems. I have a couple of plants in soil outside and I feed the autos at 1/2 strength, the photoperiods dont seem to need it yet.
I dont think soil grows need it as much as hydro as Joshua said but I do think its most important in flower
It has to be fried in cornmeal, boiled is ok for a thickening agent but not to just eat, whoever came up with that idea was hungrier than I have ever been. I was raised in Texas and Kentucky and I dont like grits or black eyed peas, I can eat hominy 3 times a day though.
Actually its not about foxtails its kind of scalping the buds by cutting off the pistils on top and a little bit of green too. It makes the buds a little more rounded on top instead of pointed. I dont think it works if you have foxtails, good or bad.
I think Light Addict is who I learned about it from, same guy that takes credit for Fluxing and has that terrible tutorial for SCROG's on GWE. If your going to do a tutorial dont stop in the middle and switch plants.